The present invention relates to an apparatus for severing a web of film. More specifically, the present invention relates to a knife and holder for cutting a web of film in a form, fill and seal packaging machine.
Typically, form, fill and seal packaging machines are utilized to package a product in a flexible container. To this end, the form, fill and seal packaging machines are utilized to seal pharmaceuticals, dairy products, wine, foodstuffs, cosmetics, and other products in flexible containers. The form, fill and seal packaging machine provides an apparatus for packaging these products in an expedient manner.
In one type of form, fill and seal packaging machine a web of heat-sealable film is passed over a former or mandrel that forms the film into a tubular shape. To effect a tubular shape, the film is folded longitudinally and heat sealed along abutting longitudinal edges. The tubular shaped film is then passed around a tubular fill system that deposits the product to be packaged into the tubular shaped film. The web of film is then sealed across its width and side seals are created. After the side seals are created the web of film is then severed by a knife or other means between the seals to create individual bags.
In a typical form, fill and seal packaging machine, the knife usually comprises an elongated piece of metal with a ground straight edge. Typically, the knife is unitary with a holder that is mounted at the sealing station of the form, fill and seal packaging machine. To this end, the unitary knife and holder is typically secured between a pair of jaws. Due to the unitary knife and holder construction, the unit typically is expensive. Moreover, because the unit is mounted between a pair of jaws, it is difficult to replace. Typically, the jaws of the machine have to be disassembled to get at the knife and holder assembly. This results in a typical replacement time of approximately one hour.
Usually, in a form, fill and seal packaging machine for making flexible containers, the knife must be changed after approximately every 40-50 manufacturing hours. Due to the expense and burdensome nature of changing the knife and holder unit the prior art knife and holder has presented some disadvantages.
The problems of the prior knife and holders are especially acute in aseptic form, fill and seal machines. In an aseptic form, fill, and seal machine the aseptics of the machine are compromised each time the knife is replaced. Accordingly, each time the knife is changed the aseptics of the machine must be reestablished before production can resume. Thusly, it is expensive, difficult, and burdensome to change the knife and holder, and results in an inordinate amount of downtime for the packaging machine especially in an aseptic packaging machine.
The prior art knife and holder has also suffered from other disadvantages. Due to the straight ground edge of the typical knife it is sometimes difficult to get a straight cut in the web of film. The film has a tendency to fold into the channel in the sealing station of the form, fill and seal packaging machine and accordingly not be subjected to a straight cut by the knife.
Accordingly, there is a need for an improved knife and holder for severing a web of film in a form, fill and seal packaging machine.